Controlling the fuel flow split between two manifolds in a turbine engine fuel distribution system can be difficult due to a variety of constraints. Those constraints may include the need for cooling flow at all operating conditions, the need to have enrichment zones on the engine, and the need to have variable, controllable flow split over a range of total engine fuel flow rates.
Some conventional fuel distribution systems inventions have addressed these constraints with two complicated valves in each nozzle, configured to provide discrete flow split levels. These valves can be expensive, heavy, and difficult to control. Further, in many cases, they do not provide variable split flow capability.
Other conventional fuel distribution systems have incorporated simpler nozzle valves with known pressure-versus-flow characteristics. Some of these have incorporated a controllable orifice at the inlet of one or both of the fuel manifolds. This series of orifices then achieves a controllable fuel flow split. However, this design is sensitive to changes in the nozzle pressure versus flow characteristic, and requires a recirculation manifold to provide cooling flow.
Embodiments of the invention represent an advancement over the state of the art with respect to split flow capability in fuel distribution systems. These and other advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.